Challenges and opportunities to design a highly active hydrodesulfurization catalyst: A comprehensive review

Hydrodesulfurization (HDS) is a catalytic process, which is used in petroleum refineries to reach sulfur levels <5 ppm of energy fuels due to its higher rate and activity for desulfurization. HDS reaction performance is mainly controlled by the sulfided phase of catalysts e.g., NiMoS/CoMoS sites for NiMo/CoMo based catalysts, and the formation of these sites depends on the catalyst design properties such as active metal dispersion, metal-support interaction, physiochemical properties like surface area/porosity and structure/morphology of catalysts based on their preparation methods/sulfidation conditions. In addition, operating conditions of reaction also govern the performance of the HDS process. A significant number of theoretical as well as experimental studies is available in literature, exploring various catalysts/technologies for HDS reaction. This review paper summarizes all these available strategies in detail and specially focuses on the effect of all mentioned parameters on HDS catalyst activity. Further, this work also discusses the required design charactertics for an ideal HDS catalyst. The prime concern of this review study is focused on highlighting and filling the gap between experimental and theoretical explanations for HDS catalysts, which is very important to analyze the HDS process performance.